In C a pointer can point to any arbitrary offset within an object or array, to a local variable somewhere on the stack, to a static variable, to read-only memory, to the first(?) of an indeterminate number of characters (hopefully) terminated by ((char)0). To the first of a statically unknown number of variables located somewhere in memory, to a variable of indeterminate type (thanks to union), to I/O devices, and also to unallocated memory since there's no bounds checking.

A reference can only point to an object or an array on the heap. Array indexing is bounds-checked.

It seems obvious to me that these restrictions make references easier to reason about than C-style pointers, and therefore easier to learn.